Marine Cold‐Air Outbreak Snowfall in the North Atlantic: A CloudSat Perspective
Marian E. Mateling, Claire Pettersen, Mark S. Kulie, Tristan L’Ecuyer
Abstract
Abstract This study analyzes the influence of marine cold‐air outbreaks (MCAO) on snowfall and cloud properties in the North Atlantic Ocean using CloudSat observations. Comparing reanalysis‐determined MCAO conditions (low‐level instability) against “non‐CAO” conditions, we find that MCAO conditions are associated with predominantly light snowfall rates (<2 mm day −1 liquid water equivalent) whereas non‐CAO conditions are more frequently associated with higher snowfall rates. Near cold‐air sources, such as sea ice or cold continents, MCAO‐forced snowfall rates tend to be more frequent and more intense. Additionally, 76% of snowing clouds identified during MCAO conditions are shallow (mean cloud top height <3 km) stratocumulus, whereas 44% (43%) of clouds in non‐CAO conditions are deeper nimbostratus (stratocumulus). With greater boundary layer instability (stronger MCAO conditions), CloudSat observes higher cloud‐top heights, reflecting a deepening boundary layer and the presence of two distinct cloud modes during MCAO conditions.